Practical solid-phase parallel synthesis of Delta(5)-2-oxopiperazines via N-acyliminium ion cyclization

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Synthetic Chemistry

Background:

• Delta(5)-2-oxopiperazines are important heterocyclic scaffolds in medicinal chemistry.
• Developing efficient and scalable synthetic routes is crucial for drug discovery.
• Solid-phase synthesis offers advantages in library generation and purification.

Purpose of the Study:

• To develop a practical solid-phase strategy for synthesizing Delta(5)-2-oxopiperazines.
• To establish a method for rapid library synthesis using N-acyliminium ion cyclization.
• To demonstrate the utility of the method by preparing a diverse library.

Main Methods:

• Solid-phase synthesis utilizing bromoacetal resins.
• Tandem acidolytic cleavage and in situ N-acyliminium ion formation.
• Enamide transformation for product stabilization.
• Library synthesis and characterization.

Main Results:

• A practical and efficient solid-phase strategy for Delta(5)-2-oxopiperazine synthesis was successfully developed.
• The key step involves tandem acidolytic cleavage and in situ iminium formation.
• A 192-member pilot library was prepared without the need for further purification.

Conclusions:

• The developed solid-phase strategy is a valuable tool for the efficient synthesis of Delta(5)-2-oxopiperazine libraries.
• This method streamlines the synthesis process, facilitating drug discovery efforts.
• The approach is robust and scalable for generating diverse compound collections.